What Are The Glock Generations?

Alien Gear Holsters Guide To Glock Generations

Anyone familiar with them has probably heard that there are several different Glock generations. The various Glock pistols get upgraded every so often with revised features, usually just a natural incremental change or new feature, that keeps the line evolving but without losing the central theme of polymer-framed, striker-fired goodness.

If you want to know what the difference is when eyeing those two Glock 9mm pistols at your local gun store, this is where you find out.

Every generation is good, but they keep getting better as they go. The most common that you'll find are Glock Gen 3, Gen 4 and Gen 5, but others are out there. Let's dive in and figure things out.

Glock Gen 1

The first Glock generation emerged sporadically - often referred to as Glock Gen 1 - as the company was getting off the ground and diversifying their product lineup. It didn't all happen overnight, to be sure.

The first Glock pistol emerged in 1984, with the Glock 17. In fact, the entire first generation of Glock pistols was literally the Glock 17 only. These guns sold in great number, but are becoming somewhat rarer as fewer are in circulation, but are out there.

The first generation had few features, being little more than a polymer frame with a bit of texturing around the entire grip, controls on the left side, some sights and...that was really about it. The barest of bones; what you needed and nothing else.

However, it was accurate enough for government work and - being ruthlessly simple - very reliable and easy to maintain. That endeared it to many militaries and police departments worldwide. You can improve on perfection, however, which led to:

Second Glock Generation

The second Glock generation was released in 1988, including updates to the Glock 17 and the release of an all-new gun, the Glock 19. The Glock 19 has been one of the most popular pistols ever created, and for good reason. It's easy to tote, easy to conceal, and easy to shoot. If you can't hit with a Glock 19, you need to not have guns and it's just that simple.

The second generation of Glock pistols only made minor revisions. Glock added a steel plate with the serial number to appease ATF regulations. The magazine design was also changed, with a new design of floorplate and a resistance insert at the bottom of the follower spring.

In 1991, Glock also introduced a new design of recoil spring, an integrated spring and guide rod. This replaced the two-piece unit that had been standard on the Gen 1.

Additionally, checkering was added to the front and rear of the grip housing for better hold on the gun.

During the Gen 2 era, additional calibers were added, including .40 S&W, .380, 10mm Auto and .45 ACP. The first of the long slide Glock pistols - the Glock 24 in .40 S&W - was created in this era, for competition use in Major power factor events. However, it was eventually discontinued just before new long slide models were introduced for Gen 3.

Late in the Glock Gen 2 product cycle, the first subcompacts were introduced. The Glock 26 in 9mm and Glock 27 in .40 S&W were launched around 1995, mostly with the civilian market in mind but also to serve as backup guns for law enforcement.

The last iteration prior to Gen 3 was the Glock 17C, which featured a ported barrel and slide for easier recoil control.

Glock Gen 3

Glock Gen 3, as it was informally called, is still available from the factory, and was introduced in 1998. Along with updates to the then-current design, new calibers - .357 Sig and .45 GAP - were added to Glock's lineup, both fitting with their 9mm architecture.

The first addition was an accessory rail to the dust cover called the "Universal Glock Rail" to allow lasers and lights to be mounted. The frame had thumb rests added above the grip on both sides, and the finger grooves - love 'em or hate 'em - were added to the grip housing. A new cross pin was installed above the trigger pin to ease stress on the locking block, lengthening service life even more.

The extractor was also revised to stick out when the pistol was loaded, thereby serving as a loaded chamber indicator.

Color entered the Glock world at this point, as FDE and olive drab finishes became options in addition to good ol' basic black. This is where the first of the Tiffany Blue glocks entered the picture.

The first single-stack Glock entered production in 2000, the Glock 36 in .45 ACP. The next ones...took some time.

Right before the end of Glock Generation 3, a few models - the Glock 22, 21, 31, 32 and 19 - were offered in a new RTF2 configuration. The Glock RTF2 - or "rough textured finish" - pistols featured revised stipling on the sides, front and back of the grips, along with fish scale serrations at the rear of the slide. However, they weren't offered for long.

Glock Gen 4

Glock Gen 4 debuted at the 2010 SHOT Show, with a host of new upgrades.

The first addition to the Gen 4 was the Glock Modular Backstrap, swappable backstraps that increased the trigger reach (and adding to the beavertail of the frame) as the user may wish. The base grip is slightly smaller than the third generation. "Gen 4" is also added to the slide so you'd know which one it was.

How to tell the difference? Well, besides the "Gen 4" on the slide, look at the backstraps. If you notice that it's definitely removable, with a line tracing the palm swell, rather than one solid housing, you got a Gen 4. If it's a solid grip housing, that's a Gen 3.

The texturing pattern on the grips from the Glock RTF2 were added to the entire Gen 4 lineup. Additionally, the magazine catches were enlarged and made reversible, so left-handed users could swap them. This caused some issues with early Gen 4 magazines, but that problem has since been corrected with newer mags.

The Generation 4 Glocks also received a dual magazine spring, which reduces felt recoil and lengthens service life.

The first two introduced were the Glock 17 Gen 4 and Glock 22 Gen 4 in early 2010, followed by the 19, 23, 26, 27 and every other 9mm-frame Glock. The large-frame Glocks, being the 10mm and .45 ACP pistols, were introduced in Gen 4 livery as of early 2013.

Two single-stack subcompacts entered production in 2014 and 2015, in the Glock 42 in .380 ACP and Glock 43 in 9mm, respectively. The Glock 43 was late to the single-stack subcompact party, having been beaten to the punch several years previously by Smith and Wesson, Walther, Springfield Armory and others. However, the 43 quickly made a name for itself as one of the best concealed carry Glock pistols available.

In 2016, a new variant called the Glock 17M was produced for the law enforcement market with some significant departures from the Glock Gen 4 pistols. It turns out that interested civilians wouldn't have to wait too long to get their own, either.

The Gen 4 has also yielded the Glock 19X, which has a full-length grip for accepting Glock 17 magazines with a 19-length slide. The Glock 19X was Glock's submission to the US military's XM17 pistol trials, though it was rejected in favor of the Sig Sauer P320 variant.

Glock Silver Slimline Pistols

Falling somewhere in between the cracks is the Glock Silver Slimline pistols. This series consists of - at the time of this writing - the Glock 48 and Glock 43X pistols.

These guns share a frame and magazine, a little wider and longer than that of the Glock 43. The difference is the length of the barrel and slide. The 48 has the same barrel (as well as slide length) as the Glock 19, and the is literally the same barrel and slide as the standard 43. However, the Silver Slimline series adds forward cocking serrations and a silver PVD finish.

Both use the new Glock Slim 01 magazine, a 10-round single-stack magazine. This beefs up the capacity compared to the 43, or reduces it in order to make the Glock 19 slimmer and lighter.

Where do they fit?!

Technically, you could classify these pistols as something like Gen 4 pistols, except that they aren't and - strictly speaking - neither really are the Glock 42 or Glock 43. The striker and firing pin are unique to the 42/43/43X/48, rather than the standard firing pin and striker in Gen 4 pistols. The frame lacks the finger grooves of the Gen 3 pistols, but also lacks the Glock Modular Backstrap of the Gen 4 and Gen 5 guns. The trigger assembly also lacks the second cross pin of Gen 3 and Gen 4 Glock pistols above the trigger guard.

So...they have some Gen 5 features, some Gen 4 features and then some features all their own.

Glock Gen 5

Glock Gen 5 was , and has yet only yielded a few pistols.

At the time of this writing, current offerings are the Glock 17 Gen 5, Glock 19 Gen 5, Glock 26 Gen 5, and the Glock 34 Gen 5 MOS, Glock 17 MOS and Glock 19 Gen 5 MOS pistols, which have a removable mounting plate should the user wish to install a red dot sight.

The Glock 45 has also been added to the lineup, which is actually a Gen 5 Glock 19X, though the base model Glock 45 is black and the 19X is in Coyote tan.

Another new addition to the Glock Gen 5 lineup is the Glock 47, which has quietly been ushered into existence. The pistol was revealed by the news that it had been selected as the new duty gun for the US Border Patrol, which was a bit of an eye-opener as a 47 had been unknown to anyone up to that point. The Glock 47 is the Glock 17 Gen 5 MOS slide on the Glock 45 frame, which has the 17's grip length but the frame length of the Gen 5 Glock 19. It hasn't been made available for commercial sale yet, but ostensibly will be soon.

The Glock Gen 5 does have some refinements, however, many of which were cribbed from the FBI's desired specs for the Glock 17M.

As far as Glock Gen 4 vs Gen 5, the Gen 5 adds the Glock Marksman Barrel. The magazine well is flared for easier reloads and a relief cut is made under the trigger guard for a higher grip. The finger grooves are omitted entirely, and ambidextrous slide controls and magazine catches are installed. The magazine baseplate is also revised.

The internal parts, which for the longest time had been virtually unchanged, have been mostly revised for the Glock Gen 5, which has required the frame to be slightly widened. The cross pin above the trigger guard has been omitted, and a new diamond-like carbon finish (a formulation of carbon with a semi-crystalline structure, unlike diamonds which are fully crystalline carbon) makes the outside tough as nails.

More will be coming, of course, but the Glock Gen 5 line is only a couple of years old. You can rest assured that more will follow.

What About Compatibility With Glock Holsters?

Now we get into the nitty gritty - compatibility and Glock Holsters.

So, prior to Glock Gen 5, the first two and second two generations would both fit the same holsters. In other words, Gen 1 and Gen 2 Glock were interchangeable and Gen 3 and Gen 4 were interchangeable, but Gen 3 and Gen 4 would not fit a Gen 1 or Gen 2 holster.

The reason? The Glock Universal Rail. It was added to the Glock Gen 3 pistols, so any holster for Gen 1 or Gen 2 - which had the same slides and mostly the same frames - would not work in a holster for the Gen 3 and later.

However, this is less of a concern today for the most part because Glock Gen 1 and Gen 2 pistols are becoming less common on the used market. You can find them, but you won't find them in stores nearly as commonly as you will find used Glock Gen 3 pistols.

So, any holster for a Glock Gen 3 - say a Glock 19 Gen 3 - will also fit the Gen 4 model. Therefore, if you have a Glock 19 Gen 3 holster, it will fit a Glock 19 Gen 4. It would also fit the Glock 23 in .40 S&W and the compacts in .357 Sig and .45 GAP with the 4-inch barrel.

However, the Glock Gen 5 does NOT fit in most Glock Gen 3 or Gen 4 holsters. Since the Gen 5 has a wider slide to accommodate revised internals and ambidextrous mag releases and slide release levers, it won't fit a Glock Gen 4 holster properly.

What about Alien Gear holsters, though?

Alien Gear Glock Holsters

As you might already know or imagine, Alien Gear Holsters offers a wide selection of holsters for Glock pistols. Alien Gear Glock holsters are available for almost every factory Glock pistol...but there are some fits that are different.

So, to explain that a little better.

Our ShapeShift Glock holsters fit the Gen 3 and Gen 4 series only. Due to the nature of the ShapeShift holster, which fully wraps the trigger guard and dust cover, only those pistols fit due to the rails.

Our ShapeShift Glock Gen 5 holsters will fit Gen 5 pistols upon release, but the Gen 5 will not fit the Gen 4/Gen 3 holster. Some purchasers have found the Gen 5 does fit the ShapeShift Glock holster, but our standards for fitment are very high. Unless our R&D team is completely satisfied, we don't say a holster fits a gun even if it would be "good enough" for others. Good enough is not good enough for us.

Additionally, Glock Gen 1 and Gen 2 pistols will not fit the ShapeShift, as they lack the Glock rail.

However, our Cloak series of holsters will fit all five Glock generations. Adjustment will be required to dial in the fit, but the adjustable height of the mounting hardware makes the requisite fitment possible.

In any case, all Glock generations can be carried using Alien Gear holsters. However, most people purchasing a Glock holster at this point in time will - in all likelihood - be carrying a Glock Gen 3 or Gen 4, which is available in the Cloak series and ShapeShift series of holster both.